Fabrication and coupling-to-fibre characteristics of laser diodes integrated with a spot-size converter having a lateral taper

Laser diodes monolithically integrated with spot-size converters operating at 1.3 mu m, and having an almost circular narrow emitted beam, have been successfully fabricated using 2 inch (50.8mm) full wafer fabrication technology. The spot-size converters consist of a lateral taper, thin-film guiding layer and ridge structure. The epitaxial structure is designed to have wide fabrication tolerance with no deterioration of device characteristics. The investigation of the coupling-loss dependence on the dimension parameters in the spot-size converters confirms that this device has a wide fabrication tolerance for these parameters. Furthermore, butt-coupling loss to fibre as low as -1.3dB is attained with alignment tolerance wide enough for passive alignment. The overall device is as short as 450 mu m, enabling high availability from one wafer.